Cane cutting apparatus

ABSTRACT

A sugar cane harvester has cane cutting apparatus for chopping cane sticks into billets. The apparatus comprises a pair of rotatable cutting elements carrying projecting axially extending blades which co-operate as the cutting elements rotate in timed relationship. The blades each have a bevelled cutting edge and are mounted so as to come into back-to-back relationship i.e. with the bevelled surfaces facing outwards, when the blades overlap. This minimizes servicing requirements and improves the quality of the cut.

This invention relates to cane cutting apparatus and in particular,though not exclusively, to harvesters for sugar cane or the likeincorporating such apparatus.

The term "sugar cane or the like" as used in this specification refersto sugar cane and other tall stick-like crops such as bamboo and kenaf.The invention is also applicable to planters e.g. for sugar cane andcassava in which cane sticks are cut into shorter lengths during theplanting operation.

The most effective apparatus for cutting sugar cane sticks into piecesor billets in a sugar cane harvester is the kind disclosed in AustralianPat. No. 222,308. Such apparatus comprises a pair of cutting elements,and a drive to contra-rotate the cutting elements in timed relationship,each cutting element having at least one blade and the blades beingpositioned to co-operate with each other to cut cane sticks passingbetween the cutting elements as the cutting elements rotate.

However, in sugar cane harvesters incorporating such cane cuttingapparatus it is necessary to maintain the blades so that when in theirclosest co-operating cane cutting position, a gap of no more than half amillimeter exists between the blades. If the gap is larger than this,the trash and the cane is not cut cleanly. In fact some of the canepieces may not be severed from each other at all -- this effect beingknown as "sausaging". Accordingly, provision has hitherto been made forthe blades to be adjusted or replaced as easily as possible. Suchadjustment or replacement is time-consuming and/or costly however,particularly in stony areas where damage to the blades by stones fedinto the harvester with the crop cannot be avoided. It is an object ofthe present invention to provide improvements in this respect.

According to the invention there is provided a harvester for sugar caneor the like as defined in claim 1 of the accompanying claims. Otherfeatures of the invention are defined in the claims following claim 1.

Embodiments of the invention will now be described by way of examplewith reference to the accompanying drawings, in which:

FIG. 1 shows a sugar cane harvester in side elevation with some of itsinternal structure including cane cutting apparatus for cutting caneindicated by broken lines;

FIG. 2 shows, again in side elevation, but on a larger scale the canecutting apparatus of FIG. 1, with certain parts of the surroundingstructure cut away for purposes of illustration;

FIG. 3 illustrates, diagrammatically and on a much larger scale, thespacial relationship of two blades of the cane cutting apparatus, as theblades come into cutting relationship; and

FIGS. 4 to 7 illustrate, somewhat diagrammatically the relationship oftwo embodiments of the present invention to previously proposed canecutting apparatus. FIGS. 4 and 7 show the embodiments of the invention.FIG. 5 shows previously proposed cane cutting apparatus; and FIG. 6shows the apparatus of FIG. 5 modified so as to achieve the same lengthof blade overlap as the embodiment shown in FIG. 4.

As shown in FIG. 1, a sugar cane harvester 10 comprises steerable frontsupport wheels 12, drivable rear support wheels 14, a control cabin 16,a housing 18 for a rear mounted engine, cane topping apparatus 20 forremoving tops from standing cane, base cutting means 22 operable tosever cane sticks from their roots, stick feeding means 24 operable tofeed severed canes into the harvester and cane cutting apparatus 26positioned to receive whole cane sticks from said stick feeding meansand operable to cut each stick into billets about 40 centimeters inlength.

A chain and slat primary elevator conveyor 28 is positioned to receivebillets at its lower end 29 from the cane cutting apparatus 26 andcarries the billets to primary trash removal apparatus 30 comprising afan 32 to pass air through the cascade of billets falling from the upperend 34 of conveyor 28. An air permeable freely rotatable roller 36admits air to trash removal apparatus 30.

A slewable chain and slat secondary elevator 38 receives billets fromelevator 28 and conveys them to secondary trash removal apparatus 40where air is drawn through the cascade of billets as they fall into atransport vehicle (not shown).

FIG. 1 also indicates the positions of drive belts 42 and 44transmitting drive forwards from the engine to the various crop handlingassemblies, a radiator housing 46 and associated fan and air cleaner 48for cooling the liquid coolant from the harvester's engine, and one 50of a pair of height-adjustable mountings for the king pins 52 of frontwheels 12.

At the forward end of the harvester 10 are provided a pair of laterallyspaced crop gathering walls 54 defining a throat and each surmounted bya rotatable tapering crop lifter 56 carrying a helical flight 58 anddriven by a hydraulic motor in a housing 60 at its upper end.

The crop gathering walls 54 lead to the base cutting means 22 and stickfeeding means 24. A drivable transverse primary feed-in roller 62 ismounted between walls 54 and has a series of radial paddles. A largersecondary feed in roller 64 having both radial paddles and curved prongsis mounted above base-cutting means 22.

Base cutting means 22 comprises a pair of contra-rotatable discs havingprojecting blades and is followed by a butt lifter roller 66 and twopairs of spaced paddle-type feeding and cleaning rollers 68, 70 and 72,74 located in a feed channel (not shown) through which all the croppasses. Rollers 72, 74 feed whole sticks of cane directly to the canecutting apparatus 26, which will now be described in detail.

As shown in FIGS. 2 and 3, cane cutting apparatus 26 comprises a pair ofspaced cutting elements 76, 78 which are driven from belt 44 through acombined clutch and flywheel 80 and a train of gears (not shown). Thetrain of gears is housed in a gearbox 82 and transmits drive from atransverse shaft (not shown) lying on the axis 84 of flywheel 80 to bothchopper drums 76 and 78, so that they rotate in opposite directions, asindicated by the arrows in the drawings, about their respective spacedparallel transverse axes 86 and 88.

The cutting elements 76 and 78 comprise respective central shafts 90 and92 journalled in end bearings (not shown) mounted on the feed channel(not shown). Each shaft has a central hollow portion 94 extending alonga major portion of its length and solid end portions 96 formed withdrive-transmitting splines 98.

In FIG. 2 several items of structure have been omitted or cut away, forpurposes of illustration. Furthermore, the lower cutting element 78 isshown in section, the section being taken at a location spaced from theends of shaft 92 in order to illustrate hollow portion 94 of the shaft.

Gearbox 82 has a removable front plate 98 retained by bolts 10. A rearwall 102 of the gearbox is formed with circular apertures 104, 106through which the cutting elements 76, 78 can be passed, after removalof two blades (to be described below) from each cutting element.

Apertures 104 and 106 serve to locate two bearing mounting plates (notshown) one for each aperture, the plates carrying bearings for theirrespective cutting element shafts 90 and 92. The bearing mounting platesare secured in position by bolts (not shown) passing through apertures108 in rear wall 102.

The shaft 90 of the upper cutting element 76 carries a split drive wheel110 having an internally splined hub 112 held in driving engagement withthe splines 98 of shaft 90 by a nut 114 and associated bolt 115. Anannular gear wheel 116 is secured by eight bolts 117 and associated nuts118 to drive wheel 110. Bolts 117 pass through slots 119 in the drivewheel whereby a small amount of angular adjustment of chopper drum 76relative to gear wheel 116 is possible, for a purpose to be described.Gear wheel 116 meshes with a drive input idler gear (not shown) formingpart of the drive train to the chopper drums 76 and 78, and it alsomeshes with a gear wheel (not shown) identical in size to itself andmounted on the shaft 92 of the lower chopper drum 78 whereby the cuttingelements 76, 78 contra-rotate about axes 86, 88.

Each of the cutting elements 76 and 78 has a pair ofoutwardly-projecting blades 120, 122 and 124, 126. The blades of eachpair each extend parallel to the axis of their respective cuttingelement across the full width of the feed channel (not shown) in whichthe cutting elements are mounted.

A pair of outwardly-projecting flanges 128 and 130 are formed onopposite sides of each of the shafts 90 and 92. The flanges extend alongthe full cutting length of the cutting elements and are apertured toreceive a series of threaded studs 132 having associated nuts 134.

Each of the blades 120, 122, 124 and 126 is clamped in position by itsstuds 132 acting through an apertured clamping plate 136 extendinglengthwise of the blade. The blades are positioned by abutment of theirrear edges against a shoulder 138 formed in each flange 128. A thinpacking plate 140 is sandwiched between each of the blades and theirrespective flanges 128.

A pair of cane feeding and guide members 142, 144 each in the form of astrip of fabric-reinforced rubber conveyor belting is mounted on each ofthe cutting elements 76 and 78. Each guide member is clamped by a seriesof bolts 146 and associated nuts 148 to flanges 150 and 152 at theleading and trailing edges respectively of the guide member, withrespect to the direction of rotation of the cutting element. The flangesare mounted on the studs 132. In use the cane feeding and guide membersassist in feeding cane sticks between the cutting elements, in guidingthe cane billets away from the cutting elements and in preventingcirculation of billets with the cutting elements as the latter rotate.

The blades 120, 122, 124 and 126 are positioned so as to overlap andco-operate with each other in pairs so as to cut cane sticks passingbetween the cutting elements 76 and 78. Each blade has first and secondparallel opposite side faces 154 and 156 respectively and a bevelledcutting edge 158 at one edge of said faces. The length of the cuttingedge extends along the full length of the blade (in a direction parallelto axes 86 and 88).

Referring now to FIG. 3, it can be seen that the width 160 of eachbevelled cutting edge 158 extends from the first side face 154 beyondthe centre line 162 of the thickness 164 of the blade to the apex 166 ofthe cutting edge. Furthermore, when the blades are in their overlappingcutting relationship shown in FIG. 3, it can be seen that the secondside face 156 of one blade 122 overlaps and is in face-to-facerelationship with the second side face 156 of the other blade 124.

A second bevelled edge 168 is formed on each of the blades of thecutting elements. The second bevelled edge extends from the second sideface 156 to the apex 166 of the cutting edge of the blade.

The lower portion of FIG. 3 illustrates diagrammatically the spacialrelationship of the blades of the cutting elements as they come intoco-operating overlapping relationship. The overlapping arcs 170 and 172represent the paths traced by the apexes 166 of the blades 122 and 124respectively.

In FIG. 3, eight positions of the blade 122 are indicated by referencesA1, A2, A3, A4, A5, A8, A9 and A10. The position of blade 124corresponding to each of these positions is indicated by references B1,B2, B3, B4, B5, B8, B9 and B10 respectively. The clearance between theblades (between second bevelled edge 168 of blade 122 and second sideface 156 of blade 124) in five of these positions is indicated byreferences C1 to C5.

Preferred ranges of dimensions for the blades of the cutting elementsare indicated below:

1. the shortest distance 174 between the second side faces 156 of theblades when the said second side faces are in parallel relationship(i.e. when equally spaced from the line 176 joining the axes 86, 88 ofrotation of the cutting elements 76, 78) lies in the range 4 to 8millimeters;

2. the overlap 178 of the arcs 170 172 traced by the apexes 166 of theblades 122, 124 (or 120, 126), the overlap being measured along the line176 joining the axes 86, 88 of rotation of the cutting elements, lies inthe range 1 to 3 centimeters;

3. the interior angle "D" between the second side face 156 of at leastone of the blades, and the second bevelled edge 168 lies in the range135° to 160° and is preferably 150°;

4. the width 180 of the second bevelled edge 168 of at least one of theblades is not greater than one quarter of the width 160 of the firstbevelled edge 158 thereof;

5. the displacement 182 of the apex 166 of the cutting edge of at leastone of the blades from the plane containing the second side face 156thereof measured at right angles to said plane is from 0.13 millimetersto 2.54 millimeters;

6. the angle between a plane containing the first bevelled edge 158 ofat least one of the blades and a plane containing the second side face156 of that blade is from 15° to 30° and is preferably 20°.

In use, severed whole cane sticks are fed, butt end first, betweencutting elements or chopper drums 76, 78 by cleaning and feeding rollers68 to 74. As the cutting elements rotate, their blades co-operate inpairs 122, 124 and 120, 126 to cut the cane into billets about 40centimeters in length. The billets are then conveyed rearwards andsubjected to the action of the two sets of trash removal apparatus 30and 40 before being dropped from the upper end of elevator 38 into atrailer (not shown).

The blades of the cutting elements begin to cut into opposite sides ofthe layer of cane sticks being fed between the cutting elements 76, 78at a position dependent upon the thickness of the cane layer. Underusual harvesting conditions, in this position the blades areconsiderably further apart than the position A10/B10 shown in FIG. 3,and the cane sticks are all completely cut through by the time theblades reach the position A8/B8.

The advantages provided by the above embodiment of the invention willnow be discussed with reference to FIGS. 4, 5 and 6.

FIG. 4 shows a pair of blades 184, 186 mounted according to theinvention, so as to come into "back-to-back" relationship i.e. withtheir second side faces 188 in overlapping and face-to-facerelationship. The amount of overlap between the apexes 190 of the bladesis indicated by the broken parallel lines 192, 194 touching the apexes.

FIG. 5 shows a pair of blades 196, 198 mounted in the manner proposedhitherto so as to come into "bevel to bevel" relationship i.e. withtheir bevelled cutting edges 200 in face to face relationship. Theamount of overlap between the apexes 202 of the blades is indicated bythe broken parallel lines 204, 206 touching the apexes.

As can be clearly seen, far less overlap of the blades is possible withthe FIG. 5 blade relationship than with that of FIG. 4.

FIG. 6 illustrates how it could be attempted to increase the overlap ofthe blades 196, 198 of FIG. 5 to that of FIG. 4, so that the apexes 202touch lines 192, 194. It is clear that in FIG. 6 the apexes 202 are verywidely spaced along the length of lines 192, 194. This means that theblades will bite into the opposite sides of a layer of cane being cut atpositions even more widely spaced than this.

Thus it is apparent that by arranging the blades "back-to-back" theinvention allows the overlap of the blades to be considerably increasedwithout increasing the separation along the length of a cane stick atwhich the two blades bite into the stick from opposite sides.

The increased overlap of the blades renders the accuracy of setting theblades relative to each other far less important than with the FIG. 5blade relationship. The invention allows a gap of up to 3 millimetersbetween the blades at their closest position to exist while stillsatisfactorily cutting cane, whereas with the FIG. 5 blade relationshipthe gap must be no more than half of one millimeter in order to cuttrash cleanly.

A further consequence of the increased overlap of the blades is that thecane cutting apparatus is less susceptible to stone damage and generalwear and tear than with the FIG. 5 blade relationship. In FIG. 5, dottedlines 208 indicate the position of the apexes of the blades after a notunusual degree of wear and stone damage. As can be seen after such wear,there is no overlap of the blades at all and effective cutting of caneand trash is out of the question. As can readily be appreciated fromFIG. 4, the same degree of wear in blades mounted according to theinvention has almost no effect on the cutting effectiveness of the canecutting apparatus.

The importance of minimizing the separation along the length of the canesticks at which the blades cut into opposite sides of the sticks arisesfrom the fact that the cane sticks have to split longitudinally betweenthe two cuts and, obviously, the shorter the split needed then the moreeasily is complete severance of the stick pieces achieved. Furthermore,with widely longitudinally spaced blades the cane sticks can bendbetween the blades, whereby no severance of the cane is achieved at all.

FIG. 7 shows a further embodiment of the invention in which blades 210,212 are arranged in "bevel-to-back" relationship. That is to say, whenthe blades are in overlapping cutting relationship, as shown in FIG. 7,the second side face 214 of blade 210 (using the same terminology as inthe previous embodiment) overlaps and is in face-to-face relationshipwith the first side face 216 of blade 212.

The FIG. 7 blade arrangement is less preferable than that of FIG. 4since the spacing of the apexes 218, 220 of blades 210, 212 along thelength of lines 192, 194 is greater than in FIG. 4. However much greaterblade overlap is achieved than in the conventional arrangement of FIG.5, and this is achieved with a much smaller blade apex separation thanin FIG. 6. Furthermore the FIG. 7 blade arrangement provides an improvedattitude of the blades relative to the bundle or mat of cane beingchopped whereby the cane sticks are cut more nearly at right angles totheir length than in the case of the FIG. 5 blade arrangement. In FIG. 7the direction of cane flow is right to left i.e. with the bevelledcutting edges 222, 224 of the blades facing in the direction of forwardmotion of the harvester.

Among modifications to the above embodiments which fall within the scopeof the invention are the use of one or three or more blades on one oreach of the cutting elements. Furthermore the cutting elements could berotated in timed relationship at different rates of rotation.

I claim:
 1. A sugar cane harvester with base cutting means operable tosever cane sticks from their roots; cane stick feeding means operable tofeed severed cane sticks into the harvester; cane cutting apparatusmounted in the harvester to receive whole cane sticks from the canestick feeding means and operable to cut each cane stick into at leasttwo pieces; conveyor means to convey cut cane sticks away from the canecutting apparatus; and drive means to drive the base cutting means, thecane stick feeding means, the cane cutting apparatus and the conveyormeans; wherein the cane cutting apparatus includes a pair of cuttingelements each of which is rotatably journaled on the harvester forrotation about parallel axes, at least one blade on each cutting elementpositioned to overlap and cooperate with a blade on the other cuttingelement to cut sticks passing between the cutting elements as thecutting elements rotate, each of said blades is formed from arectangular flat steel plate with a first side surface, a second sidesurface, substantially parallel to the first side surface, a cuttingedge running the length of the flat steel plate and spaced to one sideof a plane substantially parallel to and half way between the first andsecond side surfaces, a first beveled surface extending the length ofthe flat steel plate and from the first side surface through said planehalf way between the first and second side surfaces and to the cuttingedge, a second beveled surface extending the length of the flat steelplate and from the second side surface to the cutting edge and having awidth from the second side surface to the cutting edge that is notgreater than one fourth the width of the first beveled surface extendingfrom the first side surface to the cutting edge, clamping means forclamping each blade to a cutting element so that the cutting edge of ablade on one cutting element is parallel to the axis of rotation of thecutting element on which it is clamped and is positioned from the axisof rotation of the cutting element on which it is clamped a distancegreater than one half the distance from the axis of rotation of onecutting element to the axis of rotation of the other cutting element andso that said second side of a blade on one cutter element moves into aposition adjacent the said second side of a blade on the other cutterelement during each rotation of the cutter elements, and a cane cuttingapparatus timing and drive means for counter rotating the cuttingelements and holding the blades so that when the second side of a bladeon one cutting element is adjacent and parallel to the second side of ablade on the other cutter element, the distance between said secondsides of the two adjacent blades is at least four millimeters.
 2. Thesugar cane harvester of claim 1 wherein the overlap of the arcs tracedby the cutting edges of the blades, the overlap being measured along theline joining the axes of rotation of the cutting elements, lies in therange 1 to 3 centimeters.
 3. The sugar cane harvester of claim 1 whereinthe interior angle between the second side surface and said secondbevelled surface lies in the range 135° to 160°.
 4. The sugar caneharvester of claim 1 wherein the angle between a plane containing thefirst bevelled surface of at least one of the blades and a planecontaining the second side surface of the blade is from 15° to 30°.